In the current deployed 3G networks, the usage of Packet Switched (PS) traffic for Packet Services has boomed. A similar trend is apparent in the take up of different mobile client applications (“apps”) and the usage of cellular data connectivity as a mobile alternative to fixed line broadband network access, such as Asymmetric Digital Subscriber Line (ADSL)—often referred to a “mobile broadband”.
Both driving and responding to this trend, Higher Speed Packet Access technologies (HSPA, HSPA+) are being implemented thereby increasing the achievable throughput for these users. The main economical model for network operators is, however, based on Flat Rate Tariff or sub-versions of these rates (“unlimited” data with fair usage caps).
In certain Beyond 3G scenarios sometimes referred to as “4G”, Long Term Evolution (LTE) technology is introduced in cellular networks that already provide access using existing 3G (UMTS) and 2G (GSM-GPRS) technologies (with substantially overlapping geographical coverage).
FIG. 1 shows an example of network scenario where the coverage of the different technologies is overlapped: GSM coverage 11, UMTS coverage 12 and LTE coverage 13. There is single node or site 10 where all the three base stations of the aforementioned technologies are located: Base Transceiver Station (BTS) for GSM, Node B for UMTS and evolved NodeB (eNode B) for LTE. The network entities implementing the functionality of Controllers are connected between the respective base stations and the Core Network 101. This, the BTS from GSM is connected to the Base Station Controller (BSC), the Node B from UMTS is connected to the Radio Network Controller (RNC), both BTS and RNC are in turn connected to the Core Network 101, and the eNode B, which integrates both functionalities of base station and controller, is connected directly from the LTE access network to the Core Network 101. The core network infrastructure is composed to Circuit Switched (CS) and Packet Switched (PS) domains that are connected to the different wireless access technologies. The site 10 is in charge of redirecting the traffic from the base station to the corresponding controller and vice versa (uplink and downlink): 2G traffic 111 is handled by the BSC, 3G traffic 112 is handled by the RNC and LTE traffic 113 flows directly between the eNodeB and the Core Network 101.
At the moment, when each of these three radio technologies (GSM-GPRS, UMTS, LTE) is available for to users, every User Equipment (UE) would, by default, camp on the technology assigned the highest priority level by the mobile network operator, i.e. LTE over UMTS over GPRS. A UE is only typically redirected to another technology where there is a high likelihood of losing and/or coverage or capacity. This criterion for redirecting a user to a radio technology is not optimum for most of the applications, as the requirements (e.g., latency sensitivity) for each application is different.
On the other hand, in UMTS, the user equipment (UE) measures and reports the received level of the pilot energy-per-chip-to-total-widebandinterference-density ratio, or Ec/I0, for the handover cell selection. The pilot power determines the cell coverage area and the average number of UEs connected to the cell. Thus, the adjusting of pilot powers can be applied to balance the cell load among neighboring cells. The cell load is measured as the ratio of total transmission power to the target transmission power. Also, the current enhanced UMTS Radio Access Network (eUTRAN) standards have self-organising network and load balancing operations between base stations (enodes B) by using a direct (X2) interface to exchange information between the base stations (e.g., this information may be a ratio or percentage of the used physical resource blocks—PRBs— for a type of traffic over the total available PRBs— in the same link direction over a certain time interval.
There is therefore a need to optimise traffic allocation in the wireless networks where different mobile technologies (2G, 3G, 4G, . . . ) are overlapped for the different customers, each technology providing their own coverage and quality in terms of bandwidth available and latency in the network and having customers with mobile terminals (UEs) which support more than one or even all the technologies.